Now, however, Madison said he does not believe any civilians were armed that day.

Madison, a former FedEx employee, was arrested for allegedly shooting a police officers but was eventually cleared by a state grand jury. Federal prosecutors accuse New Orleans police officers of falsely arresting him that day.

Under direct questioning by Assistant U.S. Attorney Theodore Carter, Madison described how he found refuge from the floodwaters surrounding his eastern New Orleans home at his brother's dentist office in Gentilly, which was located at the foot of the Danziger Bridge. The morning of the storm, he and his brother Ronald had tried to walk to their mother's house in the hopes of retrieving bicycles, he said.

Madison said at the time he was "sure" he saw one of the teenagers with a gun. After he heard gunfire, he looked back and saw "them pointing an object."

Members of the Bartholomew family were walking behind the Madisons that morning. The group included two parents, Susan and Leonard, as well as their teenage son and daughter. Also with them were two other teenage boys: a 19-year-old nephew and 17-year-old friend.

After seeing the teenagers, Madison said a truck arrived at the scene and shooting exploded behind him. That truck was a Budget rental truck driven by New Orleans police Officer Michael Hunter, with many officers in the back.

Carter pressed Madison on whether he continues to believe the teenagers were armed. Madison answered no, saying, "There were no guns on the kids that I know of."

Hunter testified earlier this week, saying that as he drove along Chef Menteur Highway and approached the Danziger Bridge, seeing civilians walking before him, he fired warning shots into the air. Hunter has pleaded guilty in the case, saying he participated in a conspiracy to cover-up an unjustified shooting by police.

Frank DeSalvo, a defense attorney for Sgt. Kenneth Bowen, pressed Madison, asking him about previous statements he made in which he specifically said he saw at least one teenager with a gun in his hand. DeSalvo suggested it was investigators, who questioned him after the incident, who planted doubt in his mind about this fact.

Madison responded that during that 2006 interview he was asked to describe the gun, but couldn't. Later in his testimony he said, "I had doubt that it really was a gun. I couldn't describe it, that is what made me have doubts about it."

When he subsequently testified before the grand jury he said he believed one of the teenagers had a gun, but was not sure of this fact, DeSalvo said during questioning.

Four current and former officers -- Bowen, Sgt. Robert Gisevius, Officer Anthony Villavaso and Robert Faulcon -- are accused of shooting the Bartholomew family. One of the teenagers, James Brissette, 17, died, while four other people had serious wounds after the incident.

Several members of the Bartholomews have testified, saying they were ambushed by officers in the approaching truck. They jumped behind a concrete barrier to escape the gunfire, they said. They all testified that none of them were carrying guns. No guns were retrieved from the scene.